Our major objective is to isolate and characterize abnormal membrane components that are specific to or associated with human leukemic cells or malignant lymphoma cells, as well as to isolate normal membrane components, especially normal alloantigenic components of human lymphocytes that are linked to immunological functions. Particular effort is directed toward isolation and structural characterization of the cell surface components characteristic of malignant or immature lymphocytes and possessing a structure similar to HLA(A,B,C) antigens, e.g., human TL (thymusleukemic) antigen, and the cell membrane components unique to functional T-cell subsets, e.g., the human homologs of mouse Lyt antigens. Human lymphoid cell lines, T-cell type, B-cell type and non-T, non-B-cell type, are being used as the cell source, because they retain a variety of biological functions as well as normal cell surface structures and represent a uniform cell population of different differentiation stages. We also plan to produce human T-cell clones which possess known immunological function and use them for the present purpose. We are also generating a number of polyclonal and monoclonal antibody reagents which enable us to identify and isolate the aimed cell membrane components. The quantitative radioimmunoassay methods involving the use of either 125I-labeled cell membraneantigens or 125I-labeled antibodies against them and the peptide mapping by microfingerprinting which we have employed facilitate the present studies.